Semiconductors are the invisible enablers in modern technology. It is the heart of the revolution in the digital world today. They form the backbone of all electronic devices which people use in their daily lives-from smartphones and computers to cars and household appliances. Their unique property of controlling the current makes them integral components in virtually every piece of modern electronics. We are enlisting some Semiconductor Viva Questions for students giving practical in schools and colleges.
What is a semiconductor and explain its types?
It is a substance with conduction properties between metals and insulators. A pure semiconductor completely free from impurities is called an intrinsic semiconductor. A doped semiconductor, known as an extrinsic semiconductor, is created by adding an impurity from group 13 or group 15 to the semiconductor.
What is doping?
It is the process of addition of impurity to a pure semiconductor in order to alter its conduction properties. The impurities are p-type and n-type. p-type impurity belongs to group 13 and n-type to group 15.
Describe the significance of the energy band gap in semiconductors?
The energy band gap is the most important parameter related to semiconductors, as it determines how well the material conducts electricity. It is, in principle, the energy separation between the valence and conduction bands. The smaller this energy difference, the easier it is for electrons to be excited from the valence region into the conduction band, and thus the higher the conductivity becomes. Conversely, a large energy separation means lesser conductivity. This parameter makes it usable in a variety of transistor applications: diodes or solar cells. Sunlight falls on the photovoltaic cell, where it generates energy that enables electrons to move across the energy band gap.
What is forward bias?
A pn junction is forward biased when the positive terminal of the battery connects to the p-region and the negative terminal connects to the n-region. In a forward-biased pn junction, a small increase in voltage causes a sudden increase in current at a specific voltage called the knee voltage.
Explain the differences between p-type and n-type semiconductors?
P-type doping uses impurities that introduce holes as positive charge carriers, and N-type doping uses impurities that introduce electrons as negative charge carriers. Doping with trivalent atoms like boron induces the formation of holes, or positive charge carriers, in a P-type semiconductor. Doping a semiconductor with pentavalent atoms such as phosphorus induces an increase in the charge carrier density due to excess electrons or negative charge carriers in an N-type conductor.
These two types will then form a PN junction, which is vital for diodes and transistors since the conduction of current in a diode is unidirectional across a PN junction, facilitating rectification. This characteristic is also employed in transistors for amplification and switching of the signal. Further, multiple PN junctions are formed to construct devices that can be very complex, like the microprocessor.
Discuss the challenges involved in modern computing?
Such challenges limit scaling due to the physical characteristics of semiconductor materials, which cause problems like leakage current in transistors and negatively affect performance and energy efficiency. Another challenge is durability. Security issues arise from hardware-based attacks on memory, requiring robust encryption and isolation mechanisms for protecting sensitive data.
Practice some more semiconductor viva questions for getting a wholesome idea of what to study for college practical exams.